梯度浓度法测定蔗糖摩尔质量实验研究  

Experimental Study on the Determination of Molar Mass of Sucrose by Gradient Concentration Method

作　　者：李晓凤 董灵 郭艳 谭前前 罗骏 LI Xiaofeng;DONG Lin;GUO Yan;TAN Qianqian;LUO Jun

机构地区：[1]黔南民族师范学院化学化工学院,贵州都匀558000

出　　处：《化工设计通讯》2025年第4期46-49,59,共5页Chemical Engineering Design Communications

基　　金：贵州省科技厅基础研究计划项目(黔科合基础[2019]1297号)。

摘　　要：摩尔质量作为化学及其相关领域的关键参数,其测定在实验室中常采用凝固点降低法。鉴于传统环己烷-萘体系的环境污染问题,选用了水-蔗糖体系以减轻对环境的负面影响。稀溶液的凝固点相较于纯溶剂有所降低,这一现象与溶液中溶质分子的数量直接相关。通过对测定方法的改良,建立了以稀溶液中溶质质量为自变量、凝固点下降值为因变量的二元一次方程模型。实验过程中,逐步向水中加入蔗糖并测定各溶液的凝固点,对所得数据进行线性拟合分析,获得了相应的数据分析图及公式。利用公式中的斜率,在不同的测定条件下计算出蔗糖的摩尔质量,分别为332.56 g/mol、340.72 g/mol和335.89 g/mol,与理论值的相对误差依次为2.84%、0.46%和1.87%。这一结果表明该方法具有较高的准确性和可行性,为普通高校物理化学实验教学改革研究提供了新的案例。The determination of molar mass,a key parameter in chemistry and its related fields,is often performed in the laboratory by the freezing point depression method.In view of the environmental pollution problems associated with the conventional cyclohexane-naphthalene system,a water-sucrose system was chosen to minimize the negative impact on the environment.The freezing point of the dilute solution was reduced compared with that of the pure solvent,and this phenomenon is directly related to the number of solute molecules in the solution.By improving the measurement method,a binary equation model with the mass of solute in dilute solution as the independent variable and the decrease in freezing point as the dependent variable was established.During the experiment,sucrose was gradually added to the water and the freezing point of each solution was determined,and the obtained data were analyzed by linear fitting,and the corresponding data analysis plots and equations were obtained.Using the slope in the formula,the molar mass of sucrose was calculated under different measurement conditions as 332.56 g/mol,340.72 g/mol and 335.89 g/mol,and the relative errors with the theoretical values were 2.84%,0.46%and 1.87%in that order.This result shows that the method has high accuracy and feasibility,and provides a new case for the reform research of physical chemistry experimental teaching in general colleges and universities.

关 键 词：摩尔质量 凝固点降低 梯度浓度 水-蔗糖体系 

分 类 号：O642.1[理学—物理化学]